Boot casting



July 15, 1969 K. SANLMANN 3,454,992

BOOT CASTING Filed July 27, 196e s sheets-sheet 1 INvEN'roR KURT SANTELMANN MAW ATTORNEYS July l5, 1969 K. sANTx-:LMANN 3,454,992

BOOT CASTING 35 F/G 4 N I INVENTOR KURT SANTELMANN ATTDRNEYS July l5, 1969 K. sANTELMANN 3,454,992

BOOT CASTING Filed July 27, 1966 3 Sheets-ShedI 5 Invnn'ron KURT SANTELMANN ATTORNEYS United States Patent 3,454,992 BOOT CASTING Kurt Santelmann, Hamburg, Germany, assiguor to Phoenix Gummiwerke Aktiengesellschaft, Hamburg- Harburg, Germany, a corporation of Germany Filed July 27, 1966, Ser. No. 568,303 Claims priority, application Germany, Aug. 19, 1965, P 37,485 Int. Cl. B29c 5/00 U.S. Cl. 18-42 7 Claims ABSTRACT 0F THE DISCLOSURE A mold for casting boots is used in conjunction with a last having an upper end and a sole end. A collar-like support is firmly connected with the upper end of the last and has a flat fitting surface engaging two outer mold shells which enclose the last and which are movable to a closing position, the iiat fitting surface extends parallel to this closing movement. A sole bottom plate is provided with projections which lock the sole end of the last.

This invention relates to boot casting and refers more particularly to the manufacture of -boots by injecting thermoplastic resins and rubber mixes into a mold, starting from the bottom of the boot, the boot mold being divided in the plane of the sole and in a plane perpendicular thereto which extends parallel to the longitudinal axis of the sole. The invention is particularly concerned with a support for boot lasts in a last carrier or in a sole bottom plate.

The supporting of boot lasts provides difficulties in the case of the above-described apparatus when the length of the boot, in the -case of thermoplastic resins exceeds about 30 cm. The support furthermore provides diiiiculties when rubber mixes are to #be injected since they require a considerably higher injection pressure than the thermoplastic resins. This pressure can amount to as much as 1200 atmospheres at the nozzle in the case of rubber and up to 250 atmospheres above the atmospheric pressure in the case of plastic. The supporting is effected through a pin which is detachably connected to the mold support. The pin can ordinarily not take up the required lateral pressures since upon slight displacements of the last in the mold, the pressure on the one side is greater than on the other side, thus resulting in a difference in pressure and bending stress on the last or its support. The result is that the Iboot is made with inaccurate wall thicknesses which are out of question for a boot of high quality. In addition to this, the differences in wall thicknesses also occur at places of the boot which are subjected to increased stresses. It should be noted in this connection that the pin, the holder and the last consist of a single piece.

An apparatus of this type operates in the manner that upon the opening of the mold the last is held fast on its pin and in this condition a so-called fabric stocking is pulled on. In order to have the apparatus operate effectively, the mold shells which serve to shape the leg of the boot must be adjustable in the direction of the closing forces so that differences in the edges of the mold are compensated for in order to avoid the formation of molding flash. Since the adjustment of the mold shells is effected from the movable mold shell supports or press plates and the last pin is seated in a last support which is fixed in position, it is ditiicult to bring the axis of the closed mold shells parallel to the axis of the last precisely into the same direction as the axis of the last pin.

It a mold-shell part is shifted laterally beyond the ice axis of the last, it exerts on the support a unilateral pressure which leads to a bending of the last pin at the place of connection to the support. The last which then extends laterally oblique in the mold shells produces boots of non-uniform wall thickness.

These changes in the wall thickness occur in particular in the foot part of the boot. They are particularly disadvantageous since the greater stresses occur there.

An object of the present invention is the provision of a support of the described type which is so constructed that the disadvantages set forth above are substantially eliminated.

Other objects of the present invention will become apparent in the course of the following specification.

In the attainment of the objectives of the present invention it was found desirable to provide a construction wherein the upper end of the last has a collar-like support firmly connected to it and which is movably supported in a guide parallel to the closing direction of the outer form shells and/or so that the lower end of the last can be Iixed in projections on the sole bottom plate.

It should be noted in this connetcion that the support at the upper end of the last is used solely for short boots of a height of less than 30 cm. and for boots which consist exclusively of a single quality.

If, on the other hand, greater lengths are desired, and furthermore if a difference in quality or color between the sole and the leg is desired, it is then advisable to provide the lower end of the last also with a support. This support naturally is effective only in the first stage of manufacture when the leg, together with the leg bottom, is made. The projections on the other hand are removed during the manufacture of the sole in that the sole plate is turned, or is replaced by a sole mold in some other manner. In the second stage of the manufacture the last is already fixed by the rubber or palstic mass which has penetrated into the space between the last and the mold shell. Accordingly, the support at thelower end of the last can also by itself solve the problem to a certain extent since the ordinary mount at the upper end of the last in combination therewith already assures the necessary security with respect to the precise position of the last in the mold.

The guiding of the collar-like support at the upper end of the last is normally plane. This is caused by the plane-parallel closing procedure for the two mold shells. However, it is also possible to have the guiding take place along an arc. This is necessary when the mold shells are opened and closed while carrying out an angular movement. Both the plane-parallel and the angular movement of the shells have their advantages with respect to the precision of lit and the control mechanism.

Means are furthermore provided to block the moveability in the guide of the last. This serves to adjust the last in the proper position when the mold is closed before production is started, since when the mold is open it cannot clearly be determined whether the last in view of the movements of the shell mold parts, lies precisely in the center.

Furthermore, in accordance with the invention, the guide collar has, parallel to the direction of closing, on the side of the tip of the boot a flat fitting surface. This provides assurance for the vertically parallel adjustment of the last. Finally the collar of the last adapter should extend over the cross section of the leg. In this way a precise axial t of the last in the form shells is possible.

The invention will appear more clearly `from the following detailed description when taken in connection with the accompanying drawings showing, by way of example, preferred embodiments of the inventive idea.

In the drawings:

FIGURE 1 shows in cross section a mold used for the manufacture of a boot, some parts being shown in side elevation.

FIGURE 2. is a cross section through the support of the last.

F'IGURE 3 is a cross section of a somewhat diEerently constructed mold.

FIGURE 4 is a corresponding cross-section through the last support.

FIGURE 5 is an enlarged partial cross section illustrating the heel part of the foot last.

FIGURE 6 is a bottom view of the sole bottom plate.

The mold construction shown in FIG. 1 is suitable for making boots wherein the leg may be of a different color from the sole. The mold construction of FIG. 3 is suitable to manufacture a boot having a sole of the sarne color. The differences between the two molds reside in the larger sole space and the longer support.

FIG. 1 shows a mold carrier 1 connected with a rotary table, upon which several such molds are arranged. Opposite the mold table the insert 2 `for the inpection device is located. By turning the table the molds are brought one after the other to the injection device. The mold carrier 1 is connected by sleeves 3 and 4 carrying a pin 5 with straps 6, 7, 8 and 9. The sleeves support front and rear mold carrier parts which are separated along a plane parallel to that of the drawing. A last 10 is replaceably fastened on the mold carrier holder 13 which at the same time is the last carrier by the holding pin 11 and the holding core 12. The supporting core 12 is enclosed by a support 14 which is rigidly connected with the last 10 in such manner that it is slidably movable on the supporting core perpendicularly to the plane of the drawing. Projections 15 and :16 serve as the actual holder between the support 14 and the support core 12. The leg mold parts consist of two mold shells 17, one of which lies below the plane of the drawing and the other above it. I'hese mold shells 17 are held by the mold shell carriers 18. The sole mold plate 19 forms the bottom end of the boot. It has an injection bore hole 20 on which at the same time there is 4also seated the injection plate 21. The sole mold plate 19 is held by the carrier of the sole plate 22. The latter is movable separately from the mold shell carriers 18 and is only closed after the mold shells have already been moved against each other. For the loading and removal of the last the latter is separable into two parts, as is customary.

To provide this separation, a rod 23 is used which extends through the pin 11 into the last and makes possible longitudinal displacement of the last by corresponding elastic joints. In order to provide that after the closing of the mold shells l17 the last can be set precisely in the middle between them, an adjustment is possible which is carried out at 24 by means of a set screw (not shown). The screw li'es in the plane of the drawing and engages through the support 14 the support core 12. For displacement of the set screw an elongated hole is provided in the support 14. The flat fitting surface 25, which lies parallel to the direction of the closing, serves for the height adjustment of the last. A projection 26 serves to align the collar-like support with respect to the mold shells 17. This collar which is formed of the parts 25 and 26 extends around the last and is so seated on the upper edge thereof that it bears against its outer surfaces. In this way, in combination with the other lateral fitting surfaces, there is obtained an absolutely dependable adjustment in three dimensions of the last with respect to the outer mold shells. (see FIG. 4).

The sole mold plate 19 has at its upper outer edge a plurality of separate projections 33, 41 which grasp the last at the lower edge during the injection process, during which only a leg with leg bottom is produced, land fixes same in position. An annular hollow space 34 serves to make certain that the supporting core `12 rests firmly against the mold carrier holder 13. The last is divided along the Surface 32 lying perpendicularly to the plane of the drawing so as to facilitate the pulling off of the boot from the last 10.

FIG. 2 shows additionally the pivot curve 27 which enters into action when the mold shells carry out, as is customary during the opening and closing, angular move ments instead of a plane parallel displacement of different spacing.

FIG. 3 illustrates a somewhat similar construction wherein, however, the support 28 is made substantially longer. Furthermore, the sole mold plate 29 for the sole itself is made differently from the sole mold plate 19. As compared to the sole plate 19, the sole mold plate 29 does not have a turning plate but has on the one hand a hollow space for the leg bottom, and on the other hand a hollow space for the sole.

Since this turning plate is already the subject of German Patent 1,115,912, only one side of the sole mold plate has been shown in order to simplify the drawing.

The difference in width between the support 28 and the support 14 and the difference in shape of the sole mold plates take into consideration interchangeability of the molds for the manufacture of boots having a sole which is of the same color as, or of a different color from the leg, while retaining the same distance between the axis of rotation of the table and the injection device. The support 28 is broadened since a considerable lever action can occur at the freely suspended last in case of a unilateral introduction of the injected compounds.

FIG. 4 which is a cross section corresponding to FIG. 3 shows the flat-fitting surface 25. The collar is there continued in the lateral fitting surfaces 35 and 36 and the angularly set surfaces 30 and 31. In this way a simple mounting of the side parts -upon installation in the mold carrier is possible. The lower edges 37 and 38 are somewhat beveled in order to avoid canting upon the closing of the mold.

FIG. 5 shows an enlarged portion of the heel part of the boot last of FIG. 1 and FIG. 6 shows the sole bottom plate seen from below.

An edge 40 of the mold shell 17 surrounds the bottom mold plate 19. A projection 41 grips the last 10 from behind and in connection with other extensions 42, 43, 44, 45 such as shown in FIG. 6 makes certain that in the last cannot shift. At this stage the rubber or plastic mix is injected to form the leg with leg bottom, and small recesses are produced on the bottom of the leg, which recesses are filled up during the second injection process in the course of which the sole is formed.

It is apparent that the examples described above are capable of many variations and modifications within the scope of the present invention. All such variations and modifications are to be included within the scope of the present invention.

What is claimed is:

1. A mold for casting boots, comprising in combination with a last having an Upper end and a sole end, a support firmly connected with the upper end of the last, two outer mold shells enclosing said last and movable to a closing position, means carrying said support and said mold shells, a sole bottom plate and projections carried by said plate and locking the sole end of the last.

2. A mold for casting boots in accordance with claim 1, wherein said support comprises a collar, a core enclosed by the collar of said support and slidable in one direction relatively thereto, said means comprising a mold carrier holder firmly connected with said core.

3. A mold for casting boots in accordance with claim 1, wherein said means comprise a guide supporting said support for movement parallel to said closing movement of the mold shells.

4. A mold for casting boots in accordance with claim 3, wherein said closing movement of the mold shells eX- tends along an arc and wherein said guide has a curved surface corresponding to said arc.

5. A mold for casting boots in accordance with claim 5 3, further comprising means blocking the movement of 3,287,767 said support. 3,302,243 6. A mold for casting boots in accordance with claim 3,366,995 1, wherein said projections are conical.

7. A mold for casting boots in accordance with claim 5 1, comprising resilient supports for said projections. References Cited 272,620

UNITED STATES PATENTS 3,128,505 4/1964 Ludwig 18-42 18--30 11/1966 Ford et al 18-42 X 2/1967 Ludwig 18-30 2/ 1968 Dyken et a1. 18-36 OTHER REFERENCES 12/ 1950 France. 11/ 1961 Great Britain. 8/ 1964 Netherlands.

I. HOWARD FLINT, JR., Primary Examiner .U.S. C1. X.R. 

